Results And Discussion 31 Three IgG1 variants

Three anti-CD20 antibodies were compared in this study: standard IgG1 with fucose and native amino acids (STD-IgG1), defucosylated IgG1 with native amino acids (dFu-IgG1), and S298A/E333A/K334A-

IgG1 with fucose (AAA-IgG1) (Figure 1). STD-IgG1 is equivalent to commercially available Rituxan, which is used in the treatment of non-Hodgkin lymphomas. Rituxan is produced by Chinese hamster ovary (CHO) cells. AAA-IgG1 was also produced by CHO cells whereas dFu-IgG1 was produced by rat hybridoma YB2/0 cells. The monosaccharide composition of STD-IgG1 was similar to that of AAA-IgG1; they had almost fully fucosylated oligosaccharides (Figure 1). By contrast, the fucose content of dFu-IgG1 was 4 % (Figure 1). Thus, STD-IgG1 and AAA-IgG1 are different in amino acid sequence (wild type versus S298A/E333A/K334A), while STD-IgG1 and dFu-IgG1 differ in oligosaccharide composition (mainly fucosylated versus defucosylated). ELISA format assay demonstrated that binding activities to CD20 were identical among these IgG1 variants (data not shown).

S298A/E333A/K334A

S298A/E333A/K334A

A±oa

. Galactose

GlcNAc

STD-igG1 Fuc: 98%

. Galactose

Figure 1. The three chimeric anti-CD20 IgG1s used in this study

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